How Could a Space Elevator Survive Lightning?

That is a very good question.

If you shild your body by a conductor all around your body then it will be at same potential and will not be affected by lightning. Wear metal cloth all over your body.

Hmmm... Given that the stays holding masts up on sailboats can melted from the current of a lighting strike, wearing armor would not make me feel very comfortable.

Use supper cunductor cloth and each hair like fiber can pass thousands of amps and will remain sooooooooooooo cool. I am also suggesting this to sky jumpers through clouds and full lightning flash. Watch out for UV and Ions. Have fun and play with lightning if you wish.

Good thread!

Actually, you neglect the problem of inductance, which is familiar
to lightning protection tech.s. Any parallel conductor will experience
an induced voltage, a large one.

The short answer for a carbon fiber cable is: "cable go poof!"

Considering that lightning strikes tens of thousands of utility towers every year all over the world and lightning regularly hits skyscrapers – all with little or no damage, it seems to me that lightning strikes on a space elevator would not be problematic, as long as the support structure was conductive and well grounded.. If it was an insulator, it could be possible for there to be a large difference in charges between ground and the top. There could be some exciting moments when debarking as the charges could be quite large.

Since the space wire is non conductive and partially conductive when wet. I think you have something called resistance and if struck by lightning, I think it will fry to nothing.

When my uncle was a young TV technician, he used to use a pencil to charge himself up from the anode lead of the picture tube and, having someone open the doors for him, he would go and shock the waitresses at a nearby restaurant. The pencil's resistance slowed the time it would otherwise take to charge him up, and result in a more tolerable (I tried it. I could hardly feel it myself) experience. I have been a TV technician myself, and ben hit many times by the anode, each time a truly unnerving experience.

It seems to me that the resistance would give the 'space wire' a good chance to be able to dissipate the heat and survive.

I'm even willing to hang on the wire about 500 feet up when it is tried out ;)

Anyone willing to take bets on what I would feel?

[quote]I have been a TV technician myself, and ben hit many times by the anode, each time a truly unnerving experience..[/quote] and ofcourse for those that are unaware thats with the TV turned off "and unpluged" for 24 hours or so.

I also remember that, when one does get hit by the anode on a TV ( not nice) that the faster the finger is pulled away the larger the shock,. it appears that, and I've been shown, ouch.., when the spark travel to the finger and you pull your hand away super fast ( as you do) that the last remaining pulse still needs to reach your finger and in the race against electricity your never going to win. Except maybe by a few inches or so. and putting up with the pulse burning into your finger for the extra few seconds and pulling your finger away slowly you still get a shock although much less.

Proving I guess that Quarks increase speed over distance and time (joke) or maybe thats a quark, cut in half.

There is of course a way to deactivate it and this is not for the home user as it's probably not good for newer televisions either, the anode needs to be earthed to the earth strap that surrounds the tube with two large scew drivers with non conducting handles, one touching the anode and one touching the surrounding earth strap around the tube then bring the two metal parts of the screw drivers together where you'll see the electricity spark out of the anode down the screwdrivers to the earth strap.(and it can cause the tube glass to break if your not VERY carful So Remain Warned!) still you can always wait for two days 48 hours without the TV plugged in AT ALL. I suppose thats why they repair them at the shop.

This reminds me how many years ago if an engine was misfiring on one cylinder it would often fire properly if the HT lead was held a short distance (~3 mm) from the end of the plug, the spark jumping across. Easy with the very old-fashioned spade-with-hole type leads, the hold-down nut having long since been lost, as on Fordson Major tractors (though you often got a kick due to worn insulation). It wasn't unusual to see a button inserted into the HT lead with wires thru opposite holes for a permanent extra spark gap.

Never did understand why it worked, but the thing you describe sounds somewhat analogous.

Posted comment on Friday and on Monday had 9 emails saying replies had been posted. But I can't see a reply to my comment anywhere. Am I missing something? Also is it really necessary to send 9 identical notifications?

Since the only material suggested that would be strong enough to use is made from nano tubes which themmselves are made from carbon molecules i would have thought the cable yoke will be conductive also where is syham going to hang his farrady cage.The elevator would not work.The simpler method of attatching a bungie cord to calafornia and streching it to new yorkbefore releasing it using the gravitational pull of the midwest would work just as well as long as the release was timed to perfection.It makes sense to me

I have had a reasonable amount of experience with trying to protect equipment from lightning and there are two things I have learnt:

1. There is no guaranteed way of protecting something from damage by lightning.

2. The only thing that is predictable about lightning is that it will hit when and where you didn't think it possible could.

The amount of energy in a lightning strike is mind boggling and there have been some incredible discoveries recently of things like SPRITES that are something like 50 times more powerful than any one had thought possible and they can reach up from the couds to altitudes of 75 Km. There are also other nasties like ELVES and JETS that are even more dangerous.

If you are interested have a look at this site it has some interesting info and images about lightning

http://www.fma-research.com/spriteres.htm

Something like a space elevator would need to cope with these and I have great misgivings about the survivability of a sprite strike regardless of what precautions you take.

I can't remember the details but I believe NASA tried dangling a long length of wire from the shuttle and managed to generate a substantial amount of energy from it.It occurs to me that something like a space elevator constructed from carbon nanotubes that passes through the earths magnetosphere could have similar problem of having lager currents being induced in it. Somebody else may like to expand on this!

As I recall from earlier readings about the space elevator, lightening srikes would be a serious issue and for that reason they chose to locate the elevator out in the middle of the S Pacific somewhere that is known for its lack of lightening activity

Blowing someone's boots off and frying them to death or blasting a limb off a tree is about as far as lightning damage goes. Striking high tension power lines does nothing as we have learned how to conduct lightning safely to where it wants to go. The world's tallest skyscrapers are still there as are their top floors and roofs. Effective lightning control works and works dependably. How many airliners get blown out of the air ever year due to a lightning strike? Considering the number of flights that come near to striking range and yet go unharmed, again, the problem is just not evident. Do you think it is a matter of higher elevation and hence higher potential? Lightning has extraordinary voltage, but relatively speaking, amperage is a mere pittance.

Please bear in mind that lightning falls in the range of static electricity and therefore does NOT flow through conductors, but around them. It is not at all difficult to design a tubular static conductor to transmit static potential to ground with no structural damage. I sense a lot of fear with this issue, yet there are far more significant issues to recon with.

Lightning problems for a space elevator? Details - just details. History has shown that we can certainly overcome such details.

Perhaps what we need is to build hundreds of space elevators and design them to be struck to the most frequent and powerful lightning to the greatest degree possible, the amount of ozone released could significantly replenish the amount of ozone being depleted by other causes and hence reduce or eliminate global warming.

I say we should get to work on the space elevator immediately. We can resolve the details like lightning strikes with known, demonstrated and well understood technology. Let's move on it as soon as possible as no other project can do so much to move us away from an oil based economy to an age of abundant clean energy as can the work that can be accomplished by the creation of space elevators.

Aircraft do get blown out of the sky by lightning. All pilots are taught from square one DON'T FLY IN CUMULONUMBUS CLOUDS. The lightning isn't the main problem here things like wind shear, downdrafts, hail etc. are but because pilots give these clouds a wide berth they are also avoiding the lightning.

There is a problem with modern aircraft that has caused at least one crash that I know of. The problem is where carbon fiber is bonded to aluminium or for that matter any metal at all. If the aircraft is struck by lightning both the metal and carbon fiber will conduct it but the carbon fiber is considerably more resistive. This causes high voltages to develop between the metal and carbon fiber and arcing takes place followed by explosive destruction of the area involved. This has caused the loss of a helicopter in the North Sea when lightning struck the tail rotor causing explosive destruction of one of the blades and the loss of the aircraft.

As for the amount of energy in a lightning bolt read this site.

http://darwin.nap.edu/books/0309036801/html/30.html

it states and I quote

"The peak power and total energy in lightning are very large:

And

"lightning is one of the most damaging weather hazards"

And we are not talking about sprites, elves or jets here and they make normal lightning look tame.

When our technology reaches the point that the elevetor becomes a reality, I'm sure we will probably be able to harness the strikes and use them to power the device.

What's a space elevator?

I will try again after some serious thinking. When you are using power equipment which draws a fair amount of amperage; If you plug the wall outlet into the wall with the power switch in the on position, you will hear a load zap and see the sparks as your plug in contacts are melted away. A lot of amps want to transfer through a poor connection at the moment of contact. However, they say "The safest place, is to be inside an automobile during a lightning storm, due to the four insulating tires".

Actually the reason that the car is a safe place is due to the conductivity of the metal body. It acts as a Faraday cage. If lightning can jump through several thousand meters of air then a vulcanized rubber tire isn't going to do a great deal to stop it.

Thank you for the rubber correction!

Don't buy that idea that high voltage spark will simply cross the rubber. However, I agree that air around the can will sure get ionized with 40kV/cm potential even when air is fullt dry. In wel condition or low pressure as it will at heights, it will have a through air discharge much earlier. You can see that FL bulbs can have discharge in air at 1m for 110/220V AC.

Spave is more dangerous than Earth surface in terms of voltage discharges. There is enough charge particle shower and thin atmosphere, lots of Plasma like media.

Paerhaps look at some NASA data for what happens in real high areas, as they plan for everything. They even tried to collect charge using long tail of metal foil, which was evoporated. We get 100V/m potential above earth surface. It is not of much use on earth surface, but above earth surface, it can be of great use.

Wow, there has been a lot of "stuff" put out here!

I read the Wikipedia article on the "Space Elevator" and I just don't see how it can be done, in practical terms. Lightning strikes certainly are one of the problems, but probably one of the least, and most easily overcome, at least according to that article. But this is not a discussion on whether or not the Space Elevator can be practical. Assuming it is, and a lot of money is being spent on research based on that assumption, let us look at the possibilities to "Survive Lightning"

The Wikipedia article contained this quote: "The lightning risk can be minimized by using a nonconductive fiber with a water-resistant coating to help prevent a conductive buildup from forming." The problem is, the best, most promising material for the cable is polymer-bonded carbon nanotubes. As everyone knows, carbon is a fairly good conductor of electricity, however it also oxidizes (burns!) very easily. This would not be as great a problem in space with little oxygen, but even the reduced oxygen of sub-orbital atmospheric regions would be high enough to support combustion. This is also the area (along its length) of greatest risk from lightning. If we assume then that the material of choice (carbon nanotube) is not only a lightning attractor, but also easily damaged by the energy it absorbs (due to its low ignition point and quick oxidation) then we must seek an alternative route for the lightning.

If a space elevator could be constructed, and if (no, WHEN) it was hit by lightning, it would need an extremely large cross section, low electrical resistivity, high-temperature resistant conductor to absorb the energy and drain it off. Remember that resistance is the resistivity of a material divided by the cross-sectional area and multiplied by the distance it must travel. That is why wire-wound resistors are made from long lengths of very small diameter, low-oxidizing, heat resistant metals and why powere dissipating carbon resistors are encased in oxygen-sealing, high temperature resistant, ceramic materials. The proposed single-wall nanotube material is a good candidate for the elevator cable because it has very high strength to density ratio, i.e. low density is due to very small cross-section of it thin-wall structure. Multi-wall nanotubes are stronger but have a lower strength to density ratio. But it is also this small cross-section that would make it a very poor conductor to ground (unfortunately, not poor enough to be an insulator), and not a good candidate for lightning diversion.

That reminds me of my attempt to design a carbon rod based radiant heater. The design worked well enough for low watt-densities (heating power divided by the radiant surface area) but when surface temperatures rose with higher watt-densities, the carbon quickly degraded, smoking and even catching fire, which either broke the cermic base insulation which held it together, cutting the circuit, or fused it to the grounded metal base, causing a short circuit which allowed excess amperage flow, blowing the circuit protection devices (fuses and breakers).

Early attempts in history at using carbon as a resistive light source also failed, until it was put into a vaccuum or an inert gas and allowed an arc to strike between them. That is why we have carbon arc lamps today, however originally carbon arc lamps were thought to be too bright to be practical!

Well, we would need to have lightning rods attached, but insulated from the elevator cable. Connecting these rods and following the cable towards the earth we would need a low resistivity material (gold-silver-copper alloys?) that could handle high voltage pulses, which would allow the energy to be transferred to a point where it could be used or absorbed in some type of collector. The collector would need to appear to the lightning as a low voltage point, similar to an earth-ground, possibly a very large capacitor. Instantaneously, after a lightning surge the capacitor would need to discharge into a resistive circuit which could dissipate the energy. The lightning should not discharge directly into the resistive circuit as it could not handle the high KVA energy levels. The capacitor is needed to allow the resistive circuit time to dissipate the energy.

OK, this is theoretically possible, and possibly practical to build, but I am not an EE so I leave that to them. Another alternative would be to allow the lightning to surge to ground miles below, but that might require an exotic superconducting system to keep temperatures low and an extremely large earth ground, possibly in salt-water (ocean or large salt-lake).

Now, the other problems with the Space Elevator might be a little harder to solve!

With the replies coming back for this posting re the lightning attractiveness of the elevator ; maybe we are better off using it a a means of energy generation, rather than a method of transportation.

Andy

The problem with using lightning as a means of energy generation is that it is not a continuous power source. Both frequency of occurrence and time duration are relatively very low. Although the destructive power of its pulsed energy is awesome, we need our energy in longer and more manageable chunks, even a constant flow in many cases.

Think of lightning like a balloon that is pumped and pumped until it bursts with a loud noise. If we could divert that air pressure right before it burst and use it to do useful work, such as pump water from a reservoir into our plumbing system to take a shower, we might not be very happy with the result. We would likely turn on the shower and, assuming we had instant hot water, start to lather up. Just about the time we were good and soapy, the water would trickle to a stop, and we would have to wait minutes or hours for another balloon to fill up and be diverted to our use to finish our shower. Not very practical.